The present invention relates to optical measuring devices, and more specifically to gauges utilizing a scanned light beam to measure a linear dimension of a workpiece, or the linear distance from a reference point to a point on the workpiece upon which the beam is directed.
Optical gauges are employed in many applications, among which are those where mechanical contact is undesirable or impossible, and those where optical measurement is more rapid and/or reliable than mechanical. For example, in processing molten glass and continuous casting of metals it is necessary to maintain the surface level of the material between desired limits as the process continues. Optical gauges wherein only a light beam contacts the process material are the natural choice for such applications. Lasers provide a desirable light source for optical gauges of this type since they emit a concentrated beam of coherent radiation at a wavelength selected for best performance in the particular environment in which the gauge is to be employed.
The principal object of the invention, in a general sense, is to provide novel and improved apparatus for measuring a linear dimension with superior accuracy and reliability without physical contact with the object or material being measured.
Another object is to provide a gauge which continuously monitors the vertical level of molten materials or other process liquids and which may be installed and calibrated without shutting down the process.
A further object is to provide optical measuring apparatus of improved accuracy and reliability for making continuous and rapid measure--of the height, width, thickness, diameter, etc. of a workpiece.
Still another object is to provide optical apparatus for measuring linear distances wherein an electronically measured time period is directly commensurate with the dimension being measured.